what I know:
Terra Ven and Aqua were all best friend.
Terra Became darkness and absorb Master Xehanort after he fought him and than fought Aqua which than he lost to her where they both where in the realm of darkness Aqua sacrifices her keyblade and her armor for him to escape the realm of darkness. Aqua spent 11 years in the realm of darkness searching for the Door to light. She say 10 darksiders about to attack her but Vens and Terra Keyblade save her as they dispersed. Her travels would take her into the sea of darkness (that what i call it) while run into Ansem the Wise who wearing the Organization Xlll clothing. She asked him who are you he said he doesn't remember or doesn't know how long it been since he was here all he remembers a boy that was a Keyblade wielder she asked is it Ven or Terra but it wasn't. he would than say I used his friends to get him so he can be used for my plot from my revenge. He is the only one now that can reconnect everyone she asked whos the boys name he would look over and say Sora. and than you see the tears coming down in happiness. (i have more but that what i am reviling so far)
If you want more info pm me and i will send you the link on youtube
And now to fix all the factual errors, and grammatical ones that skew/confuse the actualities.
Xehanort posseses Terra's body by placing his OWN Heart into Terra. The two Hearts exist in one body. Terranort fights Aqua, and she beats him. In he process, Aqua is lost in the Dark Realm. 3-5 DARKSIDES attack her, but Ven and Terra's Keyblades save her by acting on their own, or guided unseen by their wielders. 12 years later, she encounters Ansem the Wise, who has forgotten almost everything in his memory, and wears an Org.XIII Cloak to protect him from the Darkness of the realm (possibly Riku's discarded robe?) He tells her a boy with a Keyblade has saved the worlds and will rescue them both as well. Upon her incorrect guesses, he tells her it is neither Ven nor Terra. A montage of numerous characters are seen saying Sora's name (Ven, Terra, Aqua, Axel, Xion, Roxas, etc.) Aqua cries.
Sorry, even though ALL of that was posted on this thread already, I had to fix it up. I hate confusion caused needlessly.
I've concluded alot, but I still don't know who that dark little guy who follows Xehanort and has a skirt-, no, suit like Dark Riku. @^@
That s Vanitas. He is the Darkness extracted from Ventus by Master Xehanort. Xehanort planned to use Ventus as his eventual second body, but when the extracted Darkness somewhat purified Ven, and Terra ended up becoming a darker soul, Xehanort began planning to use either one, leading Terra towards his own Darknes, while employing Vanitas to fight and guide Ventus in order to make him stronger.
After this darkness that becomes Vanitas is extracted, Ven's wandering Heart and comatose body are found by Sora on Destiny Islands. Sora helps reconnect Ven and his Heart, by guiding it with his own, thus connecting their Hearts by a metaphorical invisible string. This explains why Roxas (Sora's Nobody, devoid of Dark, and supposedly devoid of Light) looks like Ventus.
Possibly because of this, the darkside of Ventus, Vanitas, resembles Sora in turn, only with black hair and yellow darkness-tainted eyes. It is unknown if Vanitas looked like Sora since creation, or if he is Darkness embodied with no true form of his own, influenced by Ven's Heart, and therefore Sora's as well.
Vanitas wields a Keyblade with the Soul Eater color and blue eye because apparently those symbols and his dark mode suit are brought on by becoming/being a being of complete darkness. Vanitas was created by Darkness, Riku submitted his Heart and body to Ansem, Seeker of Darkness, who was himself emmersed in over a decades worth of darkness, knowledge, power and greed. The fact that Riku could return to the Light speaks volumes about him.
Does that help clear it up?
EDIT:
Here's the track listing for the unofficial BBS Soundtrack, in alphabetical order. Notes of interest are included:
Another Side- Slower version of the Organization XIII theme
Aqua
Aqua's Final Battle
Aqua's Luck Charms
A Battle of Great Valor
Beyond the Door
Bibido Babidi Boo
Captain Justice
Deep Space
Deep Space Battle
Destiny's Force
Destin Islands
Disney Princess
Disney Town Battle
Dive Into The Heart - Destati
Dwarf Woodlands
Dwarf Woodlands Battle
Enchanted Dominion
Enchanted Dominion Battle
The Encounter
Fall of the Land of Departure
Fate of the Unknown
The Force in You- A new mix of the version heard in Chain of Memories
Fragments of Sorrow
Go For It!
Icing on the Cake
Kairi
Land of Departure
Land of Departure Battle
Magica Mystery
Meeting Evil
Mickey Mose Club March
Mirage Arena
Neverland
Neverland Battle
Olympus Coliseum
Organization XIII- Yep. Likely what's played when Terranort and Braig speak in the end cinematic
Preparations
Radiant Garden- Much more illustrious sounding, fitting the World set in its prime.
Rage Awakened
Rowdy Rumble
Sad Princess
Scherzo Di Notte
Shrouding Dark Cloud
Stange Whispers
Terra
Tragedy
A Twinkly In The Sky
Under The Apple Trees- Zack's theme from FF7 Crisis Core, only a bit more "cowboy" sounding.
Unversed Battle
Vanitas' Sentiment- EPIC F'ING SONG
Vanitas Battle
Vanitas Final Battle- ANOTHER EPIC F'ING SONG
Ventus- Shades of Roxas' theme and The Other Promise in this one.
Ventus' Ending
Villains of a Sort
Vim and Vigor
100 Acre Woods
and one other track I can't find the name of from the list of those given. It's obviously a Disney themed world battle tune, but I don't know which one.